Defrosting semiautomatically individual refrigerators and refrigerators in multiple installations



NOV. 14, 1933. T K, Y DEFROSTING SEMIAUTOMATICALLY INDIVIDUAL REFRIGERATORS AND REFRIGERATORS IN MULTIPLE INSTALLATIONS I Filed July 6, 1931 4 Sheets-Sheet l 77/00! Mar-bury,

1,935,038 ORS NO 4, 1933- T. K.. MARBURY DEFROSTING SEMIAUTOMATICALLY INDIVIDUAL REFRIGERAT AND REFRIGERATORS IN MULTIPLE INSTALLATIONS Filed July 6, 1931 4 Sheets-Shet 2 NOV. 14, 1933. MARBUQY 1,935,038

DEFROSTING SEMIAUTOMATICALLY INDIVIDUAL REFRIGERATORS AND REFRIGERATORS IN MULTIPLE TALLATIONS Filed July 6, 195 4 Sheets-Sheet 3 I I 5' M ,v/ 97 f5 I L /a/ 'INVENTOR afi Nov. 14, 1933. T. K. MARBURY 1,935,033

DEFROSTING SEMIAUTOMATICALLY INDIVIDUAL REFRIGERATORS AND REFRIGERATORS IN MULTIPLE INSTALLATIONS Filed July 6, 1951 4 Sheets-Sheet 4 I l l a n i I I .104 :rm 1 mgwwntoz l ja Patented Nov. 14, 1933 PATENT OFFICE DEFROSTING SEMIAUTOMATICALLY INDI- VIDUAL REFRIGERATORS AND REFRIG- ERATORS IN MULTIPLE INSTALLATIONS Thomas K. Mai-bury, Memphis, Tenn. I

, Application July 6, 1931. Serial No. 548,852-

28 Claims.

This device is intended for use in connection with mechanical refrigerators or refrigerating plants and is installed in connection with the refrigerator or refrigeratingroom, as the case may be, for the purpose of controlling the flow of the refrigerating fluid through the agency of which refrigeration is accomplished.

-In this specification it will be understood that the term refrigerator will be used to designate any refrigerating enclosure such as an ordinary household refrigerator, butchers ice box or room as the case may be. The refrigerating units controlled by the device are well known and not being an inherent part of the present invention are not here shown or described.

In modern refrigerator units particularly the smaller units such as are used in homes or stores, refrigerating action is cut on as the temperature rises in the refrigerator and is cut off when the temperature drops to a certain point. In all units there is a tendency for frost to form on the refrigerating coils enclosing them eventually in a solid cake of ice which has necessarily the temperature of ice, namely 32 degrees Fahrenheit as compared with the much lower temperature of the naked coil. It results therefore that where such ice accumulates the refrigerating action is much less efiicient so that it is often necessary to defrost the coil to restore the refrigerator to eficient action. This may be done by opening up the refrigerator box but in such case unless the actuating motor of the unit is cut off much power loss is incurred. Whether the motor is cut off or not, if the box is opened,

the temperature will rise through neglect to such a high temperature that large food losses occur before the person who is defrosting the refrigerator remembers to close the door again. It also often happens that through carelessness or deliberately, the refrigerator door is left open with the current on, causing large waste of power, and overworking of the unit, in an endeavor on the part of the machinery to meet a condition for which it was not and could not be designed.

Such deliberate action of course most frequently occurs in apartments where power for operation of the unit is furnished by the lessor.

This invention relates to improvements in means for controlling refrigerator temperatures and in means for varying such temperatures and thereafter automatically restoring the device to normal conditions.

It has particular reference to a thermostatic control means which will control ordinary running temperatures, which may be adjusted to vary such-temperatures, which may be temporarily set or locked to permit defrosting of the refrigerator, and which will automatically be unlocked and returned to running conditions by a predetermined rise of temperature in the refrigerator.

The objects of this invention are:-

First, to provide means governed by refrigerator temperatures, which may be manually set to cutoff refrigerating action and permit heating 65 up of the refrigerator to accomplish defrosting, which means will automatically restore the refrigerating action on rise of temperatures to a desired point;

Second, to provide means for automatically cut- 7 ting ofi refrigerating action on excessive rise of temperature in the refrigerator, such as would be caused from leaving the door thereof open;

Third, to provide locking means whereby unauthorized restarting of refrigerating action may be prevented;

Fourth, to provide means for thermostatically controlling refrigerator temperatures;

Fifth, to provide means for manually adjusting the thermostatic control to vary the temperatures; and

Generally to improve the detail of construction of such a device.

The means by which the foregoing and other objects are accomplished and the manner of their 35 accomplishment will readily be understood from the following specification on reference to the accompanying drawings, in which:-

Fig. l is a sectional elevation of the device taken on approximately the vertical axis thereof;

Fig. 2 is a similar fragmentary section showing a different type of valve for use with the device;

Fig. 3 is a side elevation of the thermal bulb forming part of the device in Fig. 1;

Fig. 4 is a sectional elevation of a modified form of thermal bulb;

Fig. 5 is a plan view;

Fig. 6 is a sectional side elevation showing the lower bellows extended and locking dogs oscilm0 lated to permit downward movement of the lock bars;

Fig. 7 is a sectional plan taken as on the line VII-VII of Fig. l;

Fig. 8 is a fragmentary, sectional elevation of the lower portion of the device showing a modification of the construction of such part;

Fig. 9 is a vertical sectional elevation showing a modified form of the device using bellows of equal size; 119

Fig. 10 is a fragmentary side elevation of the bottom end of the device;

Fig. 11 is a fragmentary sectional detail taken on the line XI-Xl of Fig. 9;

Fig. 12 is a diagrammatic view indicating how the unit may be associated with a cooling part of the refrigerator;

Figure 13 is a longitudinal sectional view, somewhat similar to Figure 9, showing the invention modified for opening and closing a control switch;

Figure 14 is a view partly in plan and partly in horizontal section of what is shown in Figure 13.

Referring now to the drawings in which the various parts are indicated by numerals, the device comprises a substantially cylindrical casing 10. having upper and lower heads 11, 12, respectively, which are secured thereto in usual and well known manner, preferably as by screws 13. The casing 10 is preferably provided with oppositely disposed arcuate channelways 14 more clearly shown in Fig. 7, which channelways project outward from the cylindrical portion of the casing.

Disposed intermediate the top and bottom of the casing 10 is an intermediate head or disk 15, exteriorly cylindrical and closely fitting the interior of the casing 10. The disk is preferably secured to the casing by screws, as are the heads 11 and 12. Hermetically sealed to the upper side of the disk 15 is an extensible bellows 16, and to the underside of the disk a similar but larger bellows 17 is similarly secured. Closing the upper end of the bellows 16 and hermetically sealed to it is a head 18 which is provided with an upwardly extending annular boss 19 in which is secured a post 20. Preferably a bushing 21 of insulating material is disposed between the post and the boss 19 to minimize heat transference therebetween. Secured into the upper end of the post 20 is a plunger 22 which is provided with a button 23. The head 11 is tapped out to receive a threaded plug 24 on which is mounted and secured a hand wheel 25. The plug 24 is bored out to slidably receive the plunger 22. The underside of the plug 24 is recessed to receive a compression spring 26 the lower end of which rests on an enlarged portion of the post 20. The tension of this spring may be adjusted by screwing the plug 24 inward or outward. The plug 24 is screwed in'the proper distance to accomplish the desired tension on the spring before the hand wheel is placed thereon. 27 is a stop forming part of the head 11 and 28 a cooperating stop on the hand wheel which limits rotation of the hand wheel to slightly less than one complete turn.

At the lower end of the bellows 17 is a head 30 which is hermetically sealed to the bellows. Integral with and projecting downward from this head is a boss 31 into which is screwed a pull rod 32 which is provided with a finger ring or grip 33. The exterior of the boss 31 adjacent the head 30 is threaded and an annular cup shaped member 34 correspondingly threaded is secured thereon. This member is provided with oppositely disposed rack teeth 35, with which engage teeth 36 on cams 37. The cams 37 are oscillatably mounted on pins 38 which pins are carried by the casing 10.

The head 12 is provided with an annular boss 40 which is interiorly threaded to receive an exteriorly threaded plug 41. 42 is a compression spring which is disposed between this plug and a suitable shoulder on the boss 31. The

tension of this spring is adjusted by tightening or loosening the plug 41. This plug is centrally apertured to slidably receive the pull rod 32.

Resting on the upper head 18 and surrounding the boss 19 is a yoke having outwardly extending arms 45 which arms support a pair of depending bolts 46 which limit the separation of the heads 18 and 30. These bolts pass through suitable holes in the disk 15 and have heads on their lower end. 4'7 is an annular plate surrounding the member 34 underlying the head 30 which plate is supported by the heads of the bolts 46.

Hingedly secured to the outer end of the arms 45 and depending therebelow are looking rods 49 which rods lie in the arcuate channelways 14. These rods are provided at their lower end with dogs 50 which engage with the cams 37 under certain conditions.

The post 20 is slotted to receive a lever 51 one end of which is hinged on a pin 52 carried by the wall by one of the chanelways 14. This lever is also pivotally secured to the post 20 as by the pin 53 and is pivotally connected by a pin 54 to a post 55 which acts on one arm of the bell crank lever 56 whereby when the lever 51 is moved upward a needle valve 57 is pushed open. This needle valve 57 forms part of a well known type of expansion valve 58, the detail of which valve not being a part of the present invention will not be further described. In Fig. 2, the post 55 acts through the bell crank lever 56 on a modified form 57-A of valve, the action in both cases being the same.

60 is a thermal bulb, in which is disposed a volatile liquid 61 highly responsive to temperature changes. From this bulb, a tube 62 leads into the casing 10 and through a hole 63 to the center of the disk 15 thence through a vertically disposed opening 64 into both of the extensible bellows. Preferably the thermal bulb 60 is made saddle shape so that it will fit over and closely embrace a pipe 65 forming part of the suction line of the refrigerator machinery, and is held tightly thereagainst by straps 66. Such a bulb is responsive to suction line temperatures.

Fig. 4, shows a modified form of thermal bulb '70, likewise containing a volatile liquid 71 and having a tube '72 leading into the casing. Ordinarily both bellows also contain the same liquid.

In Fig. 8, the lower end of the annular member 34 is made in the form of a helix with which a complementary helix on the upper end of a rotatable plug 81 cooperates. The plug 81 is held against rotation by a pin 82 which may be released by a key 83. When so released rotation of the plug 81 will push the annular member 34 upward. 84 is a notch formed in the upper surface of the plug 81 which notch is engaged by a corresponding projection 85 from the lower surface of the member 34 andnormally prevents return rotation. The spring 42 is provided with an upwardly turned end 86 which engages in a corresponding notch or hole in the boss 87 projecting from the underside of the lower bellows head. The opposite end 88 of the spring projects downward and engages in a hole in the rotatable plug 81 so that turning of the rotatable plug 81 is accomplished against the tension of the spring. It will be noted that the adjustment of the compressive tension of the spring 42 is accomplished by the plug 41 as before and that this adjustment is independent of any twisting action on the spring.

In Fig. 9, I show a modified form of the device in which the bellows are of the same size. In this case also the valve 58 is mounted directly above the head 11 of the casing, preferably the mounting bracket being of a material which will resist the transfer of heat. 90 is a post screwed into the bushing 21 carried by the head 18 of the upper bellows, this post acting, on expansion of the bellows, directly on the bell crank lever 56 to open the valve 5'1. 91 are stops which limit the upper movement of the bellows 16. 92 are locking arms which extend downward through the lower head 12 and which are provided with collars 93 which limit their downward movement. Extending transversely across between the locking arms 92 is an oscillatable bar 94 to which is adjustably secured a latching plate 95. The lower head of bellows 1'7 has a projecting boss 96 which is tapped out to receive a threaded rod 97, this rod being provided with a slot 98 for a screw driver by means of which its position may be adjusted. 99 is a bushing exteriorly threaded which bears against the lower compression spring and which may be screwed inthe plate from the groove.

- ward or outward as before to adjust the tension erator in which 105 indicate ice trays and in which the mechanism shown in Fig. 9, is indicated as being disposed. The action of the device is as follows:

The casing and associated parts, with the expansion or suction valve, as the case may be, is assembled with the valve in usual position in therefrigerant line, and the thermal bulb is disposed inside the refrigerator. As the temperature rises within the refrigerator, expansion of the volatile liquid extends the bellows 16 against compression of the spring 26, raising the lever 51 and opening the valve 57 or 5'7-A as the case may be. Any drop in temperature permits the spring to shorten the bellows and the valve to tend to close.

The action thus described is largely similar to if not identical with ordinary thermostatic control of such a valve. Should it be desired to speed up cooling action the hand wheel 25 may be turned to loosen tension on the spring 26 and thus permit greater extension of the bellows and consequently greater valve opening. The amount of such speeding up however is limited by the post 27 and the stop 28 to one complete turn of the hand wheel 25.

Should it be desired to defrost the refrigerator the rod 32 is pulled down extending the lower bellows 1'7, and in so doing the cams 3'7 are rotated to approximately the position shown in Fig. 6, so that the dogs may pass the locking lugs on the cams. With the cams held in such position the button 23 is manually pushed downward compressing the bellows 16 until the dogs 50 pass below the lugs on the cams 37 this position being slightly lower than that shown in Fig. 6, after which the pull on the rod 32 is released and the cam lugs permitted to engage with and hold down the dogs 50 and the rods 49 of which they form a part. When locked in such position the lever 51 is pulled downward so that the valve 57 (or 5'I--A) as the case may be, is allowed to seat tightly, and positively cut oil. flow of the refrigerating fluid, thus stopping refrigerating action. Refrigerating action or cooling action having been stopped, the refrigerator will warm up and eventually reach a temperature at which the ice on the coils will be thawed out and released. Such rise of temperature cannot expand the bellows 16 since the same is locked down, it however will act to extend the bellows 1'7, and eventually will so extend that bellows that the cams 3'7 will be rotated to release the dogs 50 and automatically restore the controls to normal working condition. The tension on the spring 42 may be so adjusted by means of the plug 41 as to cause this action to take place at any desired degree of tem-' perature in the refrigerator.

Should the door of the refrigerator be left open either unintentionally or otherwise, the temperatures in the refrigerator would rise rapidly causing corresponding increase in length of the bellows- 16 and consequent wider and wider opening of the control valves in an endeavor of the machinery to reduce the temperature. Eventually such rise of temperature would cause the limit bolts 46 to seat the part 45 solidly against the top of the upper bellows and the plate 48 against the bottom of the lower bellows. Con- 'tinued heating would then extend the length of the bellows 17 which through its greater area would overcome the resisting pressure of the bellows 16 and eventually retract that bellows until it would pull the arm 51 downward and allow the valves to close and cut off entirely further refrigerating action. After such shut down refrigerating action could only be reinstated manually. In that form of device which is shown in Fig. 1, this could be done by merely pushing upward on the rod 32 to allow the bellows 16 to expand and to allow the lever 51 to open the control valve. In such case it would be necessary to hold the valve open until such time as the refrigerator had cooled down and normal action had been established.

In Fig. 8, this action is accomplished by rotation of the plug 81, this plug may be key con trolled as shown, or otherwise if it be so desired. If key controlled, the key is inserted to unlock the plug, after which the plug may be rotated and the lower bellows be shortened, through complementary action of the helical surfaces. If key controlled no unauthorized person could again start up the refrigerator. When the plug 81 is rotated to accomplish shortening of the lower bellows the projection engages with the notch 84 and prevents return rotation of the plug, this permits the device to be set to restore refrigerating action and allows the refrigerator to be shut up and left while the refrigerating machinery is chilling the refrigerator and lowering the temperature. When the refrigerator approaches normal working condition pressures on the lower bellows become so reduced that it shortens sufficiently to disengage the projection 85 from the notch 84, and the spring 42 rotates the plug 81 to original position.

In the form of the device shown in Figs. 9, 10 and 11 the bellows are locked to permit defrosting by pulling .directly downward on the bar 94 compressing as before the upper bellows 16.

The latching 95 is then turned until it engages in the groove 100 of the bushing 99 and so engaged holds the upper bellows latched down allowing the valve 57 to close. This position is maintained until the refrigerator warms up and defrosting is accomplished. When the predetermined temperature of the refrigerator is reached the lower bellows 1'7 will extend, against the action of the spring 42, pushing the pin 97 downward until it engages the cam 101, and disengages the latching plate from the groove 100. When so disengaged the plate will drop to its normal position as shown in Fig. 10. The upper bellows 16 being under heavy pressure from the excessive temperature in the refrigerator will immediately force the valve 5'7 open and permit maximum refrigeration to start.

It will be understood that the present mechanism with the exception of the thermal bulb will preferably be built into the refrigerating unit, which latter may be placed inside, or outside of the refrigerator as desired. In any event, however. the thermal bulb will be within the refrigerator so that it will be responsive to the temperatures therein.

It will be understood also that while this description has been confined to the action of a device of this kind on a valve for the control of flow of the refrigerating fluid that it may equally well be used for the opening and closing of the electric switch which operates the refrigerating mechanism and it will be distinctly understood that it so applies. The electric switch may be of the mercury tube construction, or open snap acting silver contacts and preferably would be placed on the valve body instead of the expansion valve or suction line stop valve.

Figures 13 and 14 show the alternative arrangement mentioned in the preceding paragraph. In this instance the structure is very similar to what is shown in Figure 9 and need not be described in minute detail, it being sufficient to state that there is a casing 102 containing a transverse partition element or support on opposite sides of which are located bellows 103 and 104 which might of course be of the same diameter but which are preferably of different diameters, the latter being larger than the former as likewise indicated in Figure 6. The upper bellows has connected therewith a plunger 105. Whereas this plunger was utilized for controlling a valve in the first described forms of the invention, it is here represented as engaging against a rocker arm 106 operatively connected with a mercury tube switch 107 pivotally mounted in the usual or any preferred manner and adapted to be interposed for example in the circuit to the motor which operates the pump unit of the refrigerator. Clearly, when the manual control means is operated as in the previously described forms, notably Figure 9, the action will be substantially the same as above described, the only difference being that instead of opening and closing the valve 57 in Figures 1 and 9 or 57 in Figure 2, the effect will be to control opening and closing of the mercury switch.

It should also be understood that while the embodiments are the preferred forms of the invention I reserve the right to make all such changes as do not in any way depart from the spirit of the invention or the scope of the claims hereunto appended.

Having described my invention, what I claim 1. In a refrigeration unit having means for controlling refrigeration, heat responsive means acting on said control means to initiate and control refrigeration, opposed heat responsive means acting on said first heat responsive means to render same inactive and means rendering said last mentioned means inactive through a predetermined range of temperature.

2. In a refrigeration unit having means for controlling flow of refrigerating fluid, heat responsive means acting on said flow control means to initiate and control fluid flow, opposed heat responsive means acting on said first mentioned heat responsive means to render same inactive and means rendering said last mentioned means inactive through a predetermined range of temperature.v

3. In a refrigeration unit having a valve controlling flow of refrigerating fluid, heat responsive means acting on said valve to initiate and control fluid flow, opposed heat responsive means acting on said first mentioned means to render same inactive and means rendering said last mentioned means inactive through a predetermined range of temperature.

4. In a refrigeration unit having a valve controlling flow of. refrigerating fluid, heat responsive means acting on said valve to initiate and control fluid flow, manually controlled means for rendering said heat responsive means inactive, and heat responsive means for automatically releasing said manually controlled means.

5. In a refrigeration unit having means for controlling flow of refrigerating fluid, heat responsive means acting on said control means to initiate and control fluid flow, manually controlled means for rendering said heat responsive means inactive, and heat responsive means for automatically releasing said manually controlled means.

6. In a refrigeration unit having mean for controlling refrigeration, heat responsive means acting on said control means to initiate and control refrigeration, manually controlled means for rendering said heat responsive means inactive, and heat responsive bellows means for automatically releasing said manually controlled means.

'7. In a control for a refrigerator having a normally closed valve for regulating flow of refrigerating fluid, a casing carrying said valve, 8. support secured within said casing, a pair of pressure responsive bellows having their inner ends secured to opposite sides of said support, said bellows being of unequal area, a thermal tube having a volatile liquid therein, means operatively connecting said tube with the interior of said bellows, means operatively connecting the smaller of said bellows and said valve, whereby extension of said bellows acts to open said valve, locking rods supported from the outer end of the smaller of said bellows, cams carried by said casing adjacent the outer end of said larger bellows and adapted to interlock with said locking arms, means carried by said larger bellows oscillating said cams on extension of said larger bellows, manual means to extend said larger bellows, and manual means to compress said smaller bellows; whereby said larger bellows may be extended, said smaller bellows compressed and said locking arms and cams be engaged to hold said smaller smaller of said bellows and said valve, whereby extension of said bellows acts to open said valve, latching means disposed against the outer end of the smaller of said bellows, cooperative latching means carried by said casing and adapted to interlock with said first means, means carried by the outer end of said larger bellows setting said cooperative means for engagement with said first means onextension of said larger bellows, manual means to extend said larger bellows, and manual means to compress said smaller bellows; whereby said larger bellows may be extended, said smaller bellows compressed and said latching means be engaged to hold said smaller bellows out of operative control with said valve.

9. In a control for a refrigerator having a normally closed valve for regulating flow of refrigerating fluid, a casing carrying said valve, a support secured within said casing, a pair, of pressure responsive bellows having their inner ends secured to opposite sides of said support, said bellows being of unequal area, a thermal tube, means operatively connecting said tube with the interior of said bellows, a volatile liquid in said tube and bellows, means operatively connecting the smaller of said bellows and said valve, whereby extension of said bellows acts to open said valve, manual means to compress said smaller bellows, to hold same out of operative connection with said valve, means for latching said bellows in compressed position, and means actuated by extension of said larger bellows for releasing said latching means.

10. In a control for a refrigerator having a normally closed valve for regulating flow of refrigerating fluid, a casing carrying said valve, a support secured within said casing, a pair of pressure responsive bellows, having their inner ends secured to opposite sides of said support, a. thermal tube, means operatively connecting said tube with the interior of said bellows, a volatile liquid in said tube and bellows, means operatively connecting one of said bellows and said valve, whereby expansion of said bellows acts to open said valve, manual means to compress said bellows, means for latching said bellows in compressed position, and means actuated by extension of the other of said bellows for releasing said latching means.

11. In a control for a refrigerator, having a valve for regulating flow of refrigerating fluid, a casing carrying said valve, a support secured within said casing, a pair of heat responsive bellows secured to pposite sides of said support, said bellows being of unequal cross sectional area, means establishing operative connection between the smaller of said bellows and said valve said means opening said valve an extension of said bellows, compression springs disposed in said casing and bearing against opposite ends of said bellows, means for limiting the maximum total extension of said bellows, whereby excessive temperature rise will cause said larger bellows to retract the smaller from operative connection with said valve, and means for restoring the cycle of operation, comprising manual means for compressing the larger of said bellows and for holding said bellows compressed, and means for automatically releasing said holding means on a predetermined reduction in internal bellows pressure.

12. In a control for a refrigerator, having a valve for regulating flow of refrigerating fluid, a casing carrying said valve, a support secured within said casing, a pair of heat responsive bellows secured to opposite sides of said support,

wid bellows being of unequal cross sectional area,

means operatively connecting the smaller of said bellows and said valve, said means opening said valve on extension of said bellows, means for limiting the maximum over all extension of said bellows, whereby excessive temperature rise acting through said larger bellows will withdraw the smaller bellows from operative action on said valve, and means for restoring normal action comprising manual means for compressing the larger of said bellows and for holding said bellows compressed, and means for automatically releasing said holding means on a predetermined reduction in internal bellows pressure.

13. In a refrigeration unit having means for effecting refrigeration, heat responsive means acting to initiate and control refrigeration, op-

posed heat responsive means acting on said first named heat responsive means to render same inactive and means rendering said last named means inactive through a predetermined range of temperature. a

14. In a refrigeration unit having means for establishing a flow of refrigerating fluid, heat responsive means acting on said flow establishing means to initiate and control fluid flow, opposed heat responsive means acting on said first named heat responsive means for rendering the same inactive, and means for rendering said last named means inactive through a predetermined range of temperature.

15. In a refrigeration unit having means for establishing and cutting off a circulating supply of refrigerating fluid, heat responsive means acting on said means to start and stop the same, opposed heat responsive means acting on said first named means to render the same inactive, and means for rendering said last named means inactive through a predetermined range of temperature.

16. In a refrigeration unit having means for effecting refrigeration, heat responsive means acting to control said effecting means, heat responsive means opposed to and movable parallel with the movement of said first named heat responsive means for rendering the same inactive, and means rendering said last named means inactive through a predetermined range of temperature.

17. In a refrigeration unit having means for effecting refrigeration, heat responsive means acting to control said effecting means, heat responsive means opposed to and movable axially with respect to the movement of said first named heat responsive means for rendering the same inactive, and means rendering said last named means inactive through a predetermined range of temperature.

,18. Ina refrigeration unit having means for establishing and cutting off a circulating supply of refrigerating fluid, heat responsive means acting on said means to control the operation thereof, other heat responsive means acting on said first named heat responsive means to render the same temporarily inactive, and manual means.

20. In a refrigeration unit having means for controlling flow of refrigerating fluid, heat responsive means acting on said control means to operate the same, manually operated means for rendering said heat responsive means temporarily ineffective, and fluid pressure operated means responsive to heat for automatically releasing said manually operated means.

21. In a refrigeration unit having means for controlling a refrigerant'supply, heat responsive means acting on said control means, manual means for rendering said heat responsive means inactive, and heat responsive expansible bellows means for automatically releasing said manually controlled means.

22. In a refrigeration unit having means for controlling circulation of a refrigerant, heat responsive means acting on said control means for operating the same, manual control means for rendering said heat responsive means inactive, and heat responsive means operating in opposition to said first named heat responsive means for automatically releasing said manually controlled means at a predeterminedtemperature, both of said heat responsive means being fluid operated. 1 23. In a refrigeration unit having means for controlling circulation of refrigerant, heat responsive means acting on said control means to initiate,-control and cut off refrigeration, manually controlled means for rendering said heat responsive means inactive, and heat responsive means for automatically releasing said manually controlled means, both of said heat responsive means being arranged in tandem.

24. In a refrigeration unit having means for controlling circulation of refrigerant, heat responsive means acting on said control means to initiate, control and cut oil refrigeration, manually controlled means for rendering said heat responsive means inactive, and heat responsive means for automatically releasing said manually controlled means, both of said heatresponsive means being fluid operated.

25. In a refrigeration unit having means for controlling circulation of refrigerant, heat responsive means acting on said control means to initiate, control and cut off refrigeration, manually controlled means for rendering said heat responsive means inactive, and heat responsive means for automatically releasing said manually controlled means, both heat responsive means being of the expansible bellows type.

26. In a refrigerating unit having means for controlling refrigeration, a pair of differential opposed heat responsive means one of which acts on said control means to initiate and control refrigeration, manually controlled means for rendering said one heat responsive meansineifective, the other of said heat responsive means operating to automatically release said manually controlled means at a predetermined temperature.

2'7. In a refrigerating unit having means for controlling refrigeration, a pair of differential opposed heat responsive means one of which acts on said control means to initiate and control refrigeration, manually controlled means for rendering said one heat responsive means ineffective, the other of said heat responsive means operating to automatically release said manually controlled means at a predetermined temperature, both of said heat responsive means being formed as expansible bellows containing fluid.

28. In a refrigerating unit having means for controlling refrigeration, heat responsive means acting on said control means to initiate and control refrigeration, manually controlled means for rendering said heat responsive means inactive, key released locking means for said manually controlled means, and heat responsive means for automatically releasing said manually controlled means upon release of said locking means.

THOMAS K. MARBURY. 

